Information in the Internet is transmitted as packets. A packet in the Internet is a fixed-length piece of data that is individually routed hop-by-hop from source to destination. The action of routing a packet means that each router along the path examines header information in the packet and a local database in order to forward the packet to its next hop. This local database is typically called the Forwarding Information Base or FIB. Entries in the FIB, usually structured as a table, determine to where packets are forwarded. The FIB is derived from a collective database called a Routing Information Database or RIB. This RIB is a collection of all the routing information the router “knows”; an algorithm maps the entries (routes) in the RIB to those in the FIB, which is used for forwarding.
The RIB is typically built in two ways, which may be used together: (a) static configuration, and (b) dynamic routing protocols. These protocols may be further subdivided into two groups based on the part of the Internet in which they operate: exterior gateway protocols, or EGPs, are responsible for the dissemination of routing data between autonomous administrative domains, and interior gateway protocols, or IGPs, are responsible for dissemination of routing data within a single autonomous domain. Furthermore, two types of IGPs are in widespread use today: those that use a distance-vector type of algorithm and those that use the link-state method. This description addresses the application of an algorithm to optimize a computation performed in the operation of link-state IGPs.